Environmentally friendly and high efficiency solid fuel production method using high-water-content organic waste, and combined heat and power system using same

ABSTRACT

The present invention relates to an environmentally friendly and high efficiency solid fuel production method using high-water-content organic waste, and, more specifically, relates to a solid fuel production method using high-water-content organic waste, the method comprising: (a) a waste mixing step in which high-water-content organic waste and municipal waste are introduced into a Fe-based reactor and mixed; (b) a hydrolysis step in which high temperature steam is added to the reactor and the mixture of organic waste and municipal waste is placed under pressure and is then stirred in the pressurized state so as to hydrolyse the mixture; (c) a pressure-reducing step in which the steam in the reactor is discharged and the inside of the reactor is rapidly reduced in pressure and left to stand in such a way as to give the organic waste from step (b) a low molecular weight or in such a way as to enlarge the specific surface area of the municipal waste from step (b) and thereby break apart same; (d) a vacuum or differential pressure step in which the reactor is placed under vacuum or differential pressure, and the water content of the reaction product from step (c) is removed; and (e) a solid-fuel forming step in which the reaction product from step (d) is subjected to natural drying and compression moulding so as to produce a solid fuel having a water content of between 10 and 20%.

TECHNICAL FIELD

The present invention relates to an environmentally friendly and highefficiency solid fuel production method using a high-water-contentorganic waste and a combined heat and power system using the same whilenoticeably reducing bad smell.

BACKGROUND ART

Organic waste such as sludge, livestock excretions in general is treatedusing a technology such as incineration, fermentation, direct orindirect drying, etc. In case of the incineration, it produces dioxinand a lot of harmful substance and requires a large amount of externallysupplied energy along with increased installation cost, so theabove-mentioned incineration has a disadvantage in that it is noteconomical. In addition, there is also a problem in that a large amountof energy is required so as to lower the water content from 80% to 15%in the course of direct or indirect drying, and bad smell generates fromsolid fuel during the drying process and after the drying process. Incase of the fermentation, it have some problems in that a lot of badsmell generates, and energy efficiency is low, and it takes long time totreat waste water. The marine exhaustion of waste sludge and livestockexcretions has been probated since January 2012 upon the effectivenessof the related protocol. In addition, it is expected that the marineexhaustion of food waste water which is produced in the course oftreatment of food waste will be prohibited after January 2013 also.

A technology for developing a solid fuel is going on so as to treathigh-water-content organic waste into energy source. In this case, itnecessarily needs to lower the water content below 15%. Such a solidfuel process technology is categorized into drying and carbonization. Interms of the total amount of energy, the drying is most preferred. Thebad smell generating in the course of the drying and the bad smellgenerating in the course of the storing and use of the produced fuelbecome problematic.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide anenvironmentally friendly and high efficiency solid fuel productionmethod using a high-water-content organic waste which makes it possibleto noticeably reduce bad smell.

It is anther object of the present invention to provide a combined heatand power system using a solid fuel produced in the above manner.

TECHNICAL SOLUTION

To achieve the above objects, as one aspect of the present invention,there is provided an environmentally friendly and high efficiency solidfuel production method using a high-water-content organic waste,comprising:

(a) a waste mixing step where a high-water-content organic waste and amunicipal solid waste are inputted and mixed in a Fe-based reactor; (b)a hydrolysis step where a mixture of the organic waste and the municipalsolid waste is pressurized by adding high temperature vapor into thereactor and is agitated in the pressurized state for thereby hydrolyzingthe mixture; (c) a depressurization step where the reactor is controlledto remain in normal state after the interior of the reactor is suddenlydepressurized by discharging the vapor from the interior of the reactor,and the mixture is crushed by depolymerizing the organic waste treatedthrough the step (b) or by increasing the specific surface area of themunicipal solid waste treated through the step (b); (d) a vacuum ordifferential pressure step where water is eliminated from the reactanttreated through the step (c) by providing the vacuum or differentialpressure condition to the reactor; and (e) a solid fuel preparation stepwhere a solid fuel of which the water content is 10˜20% is prepared bynaturally drying the reactant treated through the step (d).

To achieve the above objects, as another aspect of the presentinvention, there is provided a combined heat and power system which usesthe solid fuel produced by the above-described method.

Advantageous Effects

The present invention is characterized in that the solid fuel may beproduced by efficiently drying the internal water of the organic wastein such a way to much more effectively degrade the organic matter andbad smell with the aid of the degrading power of vapor radical and thepromoted peptone reaction by the Fe reaction catalyst by inputting andmixing high-water-content organic waste and municipal solid waste into aFe-based reactor and adding high temperature and pressure vapor and insuch a way to completely crush and degrade the organic waste based onthe sudden depressurization. In particular, the present invention makesit possible to produce solid fuel within a short time by greatlyenhancing the efficiency of drying in such a way that the non-degradedorganic waste is depolymerized through the sudden depressurization afterhigh temperature and pressure vapor is inputted and that the specificsurface area is increased by expanding the municipal solid waste.

In addition, the solid fuel produced according to the present inventionmay be provided as a good energy source which may substitute fossilenergy thanks to its high calorific power. So, it is possible toefficiently generate electricity based on the combined heat and powergenerator system using the above mentioned energy source.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating a treatment system of a high-water-contentorganic waste according to the present invention.

FIG. 2 is an ion product change and permittivity change curve of water.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention is directed to an environmentally friendly andhigh efficiency solid fuel production method using a high-water-contentorganic waste which makes it possible to efficiently dry the internalwater of the organic waste in such a way to much more effectivelydegrade the organic matter and bad smell with the aid of the degradingpower of vapor radical and the promoted peptone reaction by the Fereaction catalyst by inputting and mixing high-water-content organicwaste and municipal solid waste into a Fe-based reactor and adding hightemperature and pressure vapor and in such a way to completely crush anddegrade the organic waste based on the sudden depressurization.

Hereinafter the present invention will be described in detail.

The present invention is directed to a solid fuel production methodusing a high-water-content organic waste, which includes (a) a wastemixing step where a high-water-content organic waste and a municipalsolid waste are inputted and mixed in a Fe-based reactor; (b) ahydrolysis step where a mixture of the organic waste and the municipalsolid waste is pressurized by adding high temperature vapor into thereactor and is agitated in the pressurized state for thereby hydrolyzingthe mixture; (c) a depressurization step where the reactor is controlledto remain in normal state after the interior of the reactor is suddenlydepressurized by discharging the vapor from the interior of the reactor,and the mixture is crushed by depolymerizing the organic waste treatedthrough the step (b) or by increasing the specific surface area of themunicipal solid waste treated through the step (b); (d) a vacuum ordifferential pressure step where water is eliminated from the reactanttreated through the step (c) by providing the vacuum or differentialpressure condition to the reactor; and (e) a solid fuel preparation stepwhere a solid fuel of which the water content is 10˜20% is prepared bynaturally drying the reactant treated through the step (d).

In the present invention, the step (a) is a step wherehigh-water-content organic waste and municipal solid waste are inputtedand mixed in a Fe-based reactor. The high-water-content organic waste isone or at least one selected from the group consisting of livestockexcretions, sewage sludgy, and food waste and contains more than 80% ofwater content, and the municipal solid waste preferably contains kind ofpaper and plastics. The municipal solid waste containing such paper andplastics each having increased specific surface area reacts whileexpanding together with the organic waste which was depolymerized bymeans of the depressurization in the depressurization step, so thedrying efficiency may be maximized. Since the plastics-based municipalsolid waste which is a kind of a petroleum-based organic substance iscontained, it is possible to enhance the low calorific power of theproduced solid fuel. Preferably, the municipal solid waste contains50˜55% by weigh of paper, and 40˜45% by weight of plastics.

In the step (a), it is preferred that the high-water-content organicwaste and the municipal solid waste are inputted and mixed at a ratio of3.5˜4:0.5˜1. In addition, it is more preferred that thehigh-water-content organic waste and the municipal solid waste areinputted and mixed in the reactor at a filling ratio of 70˜90%. Sincehigh temperature and pressure vapor may be supplied from outside thereactor even though the waste, which will be treated, is inputted intothe reactor at such high charging rate, and the contact-based reactionwith the saturated vapor can be maintained, so that it is possible toenhance the efficiency of reaction in the highest process capacity ofthe wastes.

In the present invention, the step (b) is a step where a mixture of theorganic waste and the municipal solid waste is pressurized by supplyinghigh temperature of vapor into the reactor, and the mixture is agitatedin the pressurized state and is hydrolyzed. The substance belonging tothe organic waste is degraded and depolymerized by the pressurization,and the bad smell containing sulfuric acid is degraded, so the watercontent of the organic waste may be greatly lowered thanks to the hightemperature while eliminating bad smell. At this moment, it is preferredthat the mixture may be agitated and undergo the hydrolysis reactionafter the internal pressure of the reactor is made to 20˜25 atm bysupplying the vapor of 200˜250° C. into the reactor. FIG. 2 illustratesan ion product ([H+][OH−]change and permittivity change of water.Referring to FIG. 2, the ion product reaction is most active at thetemperature of 200˜250° C. and shows 1,000 times higher activity ascompared with the room temperature. Since the permittivity lowers to ⅓˜¼as compared with the room temperature, a potential difference occursbetween the ions, which would result in increased organic substancedegradation performance. If it is below the range of the abovetemperature and pressure, it is hard to obtain the desired effect, andwhen it is above the range of the above temperature and pressure, theloss in energy may occur.

In the step (b) of the present invention, since the supply of the vaporis performed using a boiler which is connected to the reactor, theorganic waste in the reactor comes into contact with the vapor from theboiler and physically and chemically reacts for thereby greatlyenhancing the efficiency of the reaction without any procedure where thewater changes to high temperature water in such a way that it is sprayedwhile coming into direct contact with the low temperature organic waste.In addition, since the vapor is supplied using the externally suppliedboiler, any phenomenon where it reacts with high temperature water doesnot occur, so the reaction may be maintained even when the amount of thewaste increases. Therefore, the mixture of the waste, which will betreated, is charged up to 70˜90% of the reactor, thus causing acontact-based reaction with the vapor.

Since the hydrolysis is performed inside of the Fe-based reactor, theefficiency of the reaction may be greatly enhanced thanks to thecatalyst reaction of Fe, in particular the promoted peptone reaction inthe region where the saturated vapor occupies in the reactor, and anorganic membrane of 1˜2 mm is formed in the inner side of the reactorbased on the process and operation of the reactor, so it is possible toprevent any corrosion due to NaCl, etc.

The step (c) of the present invention is a step where the reactor iscontrolled to remain in normal state after the pressure inside of thereactor is suddenly depressurized by discharging the vapor from theinterior of the reactor, so that the organic waste treated through thestep (b) is depolymerized or the specific surface area of the municipalsolid waste treated through the step (b) is increased, and the municipalsolid waste is crushed, more specifically, the step (c) is a step wherethe reactant pressurized by high temperature vapor is suddenlydepressurized, and the volume of increased, thus depolymerizing thereactant or crushing the reactant. Since the volume of the municipalsolid waste in the form of raw material is suddenly expanded through thesudden depressurization, and the specific surface area is increased, sothe drying time may be shortened because such municipal solid waste isreacted with the water-content organic matter and is dried, thus greatlyenhancing the efficiency of the drying. Here, it is preferred that thepressure is suddenly depressurized so that the atmosphere may become0.9˜1.1 atm by discharging the vapor inside of the reactor for 10˜120seconds.

In addition, the step (d) of the present invention is a step where themoisture is eliminated from the reactant treated through the step (c) byadopting the vacuum or differential pressure condition to the reactor.It is preferred that the moisture is eliminated by 5˜10% from thereactant treated through the step (c) by adopting the vacuum ordifferential pressure condition or 10˜15 minutes to the reactor usingthe vacuum pump connected to the reactor.

Also, the step (e) of the present invention is a step where the reactanttreated through the step (d) is naturally dried for thereby producingsolid fuel of which the water content is 10˜20%. It is preferred thatthe solid fuel having low calorific power of above 5,000 kcal/kg isproduced.

According to another aspect, the present invention relates to thecombined heat and power generator system using the solid fuel producedusing the above-described method. Namely, the present invention providesthe combined heat and power generator system characterized in that thesolid fuel (RDF) is produced from high-water-content organic waste andmunicipal solid waste, and superheated vapor is produced by supplyingthe solid fuel to the RDF-based burner and boiler, and electricity maybe generated by the steam-based power generation system which uses thesuperheated vapor.

Hereinafter, the present invention will be described in detail alongwith the exemplary embodiment.

EMBODIMENTS Embodiment 1

A batch reactor made of a Fe material and having a dimension of 5 m³ wasmanufactured. 3.5 tons of livestock excretions of which thewater-content was 80˜85% and 0.5˜1 tones of paper Municipal Solid Waste(MSW) were inputted into the reactor as soon as possible, and the inputport of the top of the reactor was closed. Upon completing the input,the livestock and the MSW were mixed, and vapor of 210° C. was suppliedfor the internal pressure of the reactor to become 23 atm. At this time,the inputted saturated vapor or superheated vapor reached the reactioncondition within about 3˜5 minutes in the vapor supply-dedicated boilerof the top of the previously prepared reactor, so the supply of thevapor was stopped. The supplied vapor and target waste were agitated at10˜15 rpm so that the supplied vapor and target waste physically andchemically reacted. When the reaction reached a condition below thepreviously set temperature and pressure while the reaction was beingperformed, the saturated vapor or superheated vapor was intermittentlysupplied so as to maintain the atmosphere of 23 atm at 210° C. Theabove-described state was maintained for 30˜60 minutes depending on thephysical property of the treatment target in order for the peptonereaction to take place enough based on the catalyst operation by thevapor, the treatment target organic matter and the Fe-based reactor.

Next, the organic matter and the organic cell or MSW, which had not beendegraded during the above-mentioned reaction, were depolymerized orcrushed by quickly discharging the vapor through the vapor dischargeport by opening the pressure reducing valve until the pressure becamethe atmospheric pressure (1-atm) within 2 minutes. About 5˜10% of thetotal water of the reactant was eliminated by performing the vacuum(differential pressure) process for about 10˜15 minutes using theexternal vacuum (differential pressure) pump so as to eliminate thewater from the reactant in the reactor under the high vacuum ordifferential pressure condition after the processes for depolymerizingand crushing the reactant. The product produced after the reaction wasmoved to the natural drying place and was naturally dried, so that thefinal solid fuel of which the water content was 15% was produced.

Comparison Example 1

The solid fuel was produced by the method of the first exemplaryembodiment, wherein the solid fuel was produced without adding themunicipal solid waste (MSW).

Comparison Example 2

The solid fuel was produced by the method of the first exemplaryembodiment, wherein the solid fuel was produced without performing aprocess for suddenly depressurizing by discharging the vapor after thepressurization.

Experiment and Result

The changes of the water content amount based on the producing time(drying time) of the solid fuel according to the above exemplaryembodiment were measured using the non-treated high-water-content wasteand the comparison examples 1 and 2 as the control group, and the resultof the measurement is shown in Table 1.

TABLE 1 Comparison Comparison Drying High-water-content EmbodimentExample Example time(hour) waste(wt %) 1(wt %) 1(wt %) 2(wt %) 0 83 5984 60 10 80 36 81 47 20 77 10 75 36 40 65 5 63 22 60 61 4 56 15

As shown in Table 1, in case of the comparison example 1 where thetreatment was performed without the municipal solid waste, the treatmentshowed the almost same drying speed as the high-water-content wastewhich was not treated. Such a result seems to come from the fact thatthe reactant became a gel state phase thanks to the depolymerization ofthe organic matter and the external discharge of the level in themolecules, so only the water being on the top of the gel was evaporated,and the water at the bottom of the gel was not evaporated. In case ofthe comparison example 2 where the treatment was performed without thesudden depressurization process, it is confirmed that the drying speedduring the natural drying was not affected because the increase rate ofthe specific surface was low. In case of the embodiment 1 of the presentinvention, about 10% of the water content rate was obtained after about20 hours elapsed, which represents that the efficiency of the solid fuelmanufacture is very high.

As a result, it is possible to confirm that the time elapsed until thewater content rate became 10% through the sudden depressurization andvacuum processes by adding the municipal solid waste was shortened morethan 2 times.

In addition, a result of the analysis with respect to the phases of themunicipal solid waste used in the embodiment 1 and the comparisonexample 2 is as follows.

TABLE 2 plas- others Foods paper tics fibers wood rubbers(incombustible) total 1.07 51.3 42.6 0.07 3.2 1.74 0.02 100(%)

In addition, as a result of the measurements of the calorific values ofthe solid fuel prepared according to the embodiment 1 of the presentinvention and the solid fuel prepared according to the comparisonexample 1, the case of the embodiment 1 where the municipal solid wastewas added showed the average heating value of 5,000 kcal/kg which was500 kcal/kg higher than the comparison example 1. Namely, it seems thatthe drying speed was increased since the specific surface area wasenlarged in the sudden depressurization process thanks to the paper ofmore than 50% and the plastics of more than 40% both contained in themunicipal solid waste, and the heating value of the solid creature wasincreased thanks to the plastics which are the petroleum-based organicmatter. The average heating value is shown in Table 3 (unit: kcal/kg).

TABLE 3 Embodiment 1 Comparison example 1 Municipal Solid Waste Sludge5000 4500 4700 4300

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described examples are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the meets and bounds of theclaims, or equivalences of such meets and bounds are therefore intendedto be embraced by the appended claims.

1. An environmentally friendly and high efficiency solid fuel productionmethod using a high-water-content organic waste, comprising: (a) a wastemixing step where a high-water-content organic waste and a municipalsolid waste are inputted and mixed in a Fe-based reactor; (b) ahydrolysis step where a mixture of the organic waste and the municipalsolid waste is pressurized by adding high temperature vapor into thereactor and is agitated in the pressurized state for thereby hydrolyzingthe mixture; (c) a depressurization step where the reactor is controlledto remain in normal state after the interior of the reactor is suddenlydepressurized by discharging the vapor from the interior of the reactor,and the mixture is crushed by depolymerizing the organic waste treatedthrough the step (b) or by increasing the specific surface area of themunicipal solid waste treated through the step (b); (d) a vacuum ordifferential pressure step where water is eliminated from the reactanttreated through the step (c) by providing the vacuum or differentialpressure condition to the reactor; and (e) a solid fuel preparation stepwhere a solid fuel of which the water content is 10˜20% is prepared bynaturally drying the reactant treated through the step (d).
 2. Themethod of claim 1, wherein in the step (a), the high-water-content wasteis one or more than one waste selected from the wastes of livestockexcrements, sewage sludgy and food waste and contains the water contentof more than 80%, and the municipal solid waste contains paper andplastics.
 3. The method of claim 2, wherein in the step (a), thehigh-water-content waste and the municipal solid waste are inputted at aratio of 3.5˜4:0.5˜1 and are mixed.
 4. The method of claim 2, wherein inthe step (a), the high-water-content waste and the municipal solid wasteare inputted at a filling ratio of 70˜90% into the Fe-based reactor andare mixed.
 5. The method of claim 1, wherein in the step (b), themixture of the organic waste and the municipal solid waste ispressurized so that the internal pressure of the reactor becomes 20˜25atm by adding the vapor of 200˜250° C. to the reactor using a boilerconnected to the reactor.
 6. The method of claim 1, wherein in the step(c), the pressure is suddenly depressurized for the atmosphere to become0.9˜1.1 atm by discharging the vapor from the interior of the reactorfor 10˜120 seconds.
 7. The method of claim 1, wherein in the step (d),the vacuum or differential pressure condition is provided to the reactorfor 1015 minutes using a vacuum pump connected to the reactor forthereby eliminating 5˜10% of the water from the reactant treated throughthe step (c).
 8. The method of claim 1, wherein the solid fuel preparedin the step (e) has a low calorific power of above 5,000 kcal/kg.
 9. Acombined heat and power system characterized in that electricity isgenerated using superheated vapor produced by supplying the solid fuelto a reactor wherein the solid fuel is produced by the method ofclaim
 1. 10. A combined heat and power system characterized in thatelectricity is generated using superheated vapor produced by supplyingthe solid fuel to a reactor wherein the solid fuel is produced by themethod of claim
 2. 11. A combined heat and power system characterized inthat electricity is generated using superheated vapor produced bysupplying the solid fuel to a reactor wherein the solid fuel is producedby the method of claim
 3. 12. A combined heat and power systemcharacterized in that electricity is generated using superheated vaporproduced by supplying the solid fuel to a reactor wherein the solid fuelis produced by the method of claim
 4. 13. A combined heat and powersystem characterized in that electricity is generated using superheatedvapor produced by supplying the solid fuel to a reactor wherein thesolid fuel is produced by the method of claim
 5. 14. A combined heat andpower system characterized in that electricity is generated usingsuperheated vapor produced by supplying the solid fuel to a reactorwherein the solid fuel is produced by the method of claim
 6. 15. Acombined heat and power system characterized in that electricity isgenerated using superheated vapor produced by supplying the solid fuelto a reactor wherein the solid fuel is produced by the method of claim7.
 16. A combined heat and power system characterized in thatelectricity is generated using superheated vapor produced by supplyingthe solid fuel to a reactor wherein the solid fuel is produced by themethod of claim 8.